The displacement of a surface wave across the ocean yields vertical and horizontal movement of the water, the combination of these movements generating orbital motion of bodies placed on the surface and at some depth. The amplitude of the orbital motion is exponentially reduced with depth, in practical terms motion does not occurring at a depth which is equivalent to half the wave length of the propagation.
Water vehicles are submitted to the actions of waves and currents and also bear the effects of wind which, combined to the drive of the kind of propulsion usually employed, sails or motor, perform complex oscillatory motions made up of horizontal, vertical and rotational components.
Several proposals have been advanced aiming at utilizing wave energy for producing useful work for, among others, the displacement or motoring of water vehicles.
Thus, U.S. Pat. No. 1,622,173, to T. R. Bean et al., is directed to means utilizing the motion of the waves and the kinetic energy of a ship in its rising and falling movements for propelling the ship and driving its auxiliary machinery. To this goal, water turbines enclosed in cylinders are arranged in the ship in such manner as to operate in response to the relative vertical motions of the water and the ship and the oscillatory motions of the turbines are transformed into continuous rotary motion for application to the ship's screws or auxiliary machinery.
U.S. Pat. No. 4,481,002 to Gargos, G. relates to a boat having an external float pivotally fixed to the boat. Through linkage, the motion of the float relative to the boat resulting from wave motion drives a dual cylinder pump. The pump admits water from the body of water in which the boat is suspended and pressurizes that water for direction aft as a means for propulsion.
Published US Application 20050126849 A1 to Pearson, J. B. et al. relates to a selective damping apparatus comprising at least one sensor (7) for detecting, and producing signals indicative of at least the frequency and amplitude of vibrations of a first structural component (“the resonant structure”) (6) having one or more resonant frequencies, at least one vibration generator (40) for generating damping vibrations for application to the resonant structure, a controller (8) for controlling the operation of the vibration generator (40) in delayed response to the signals produced by the at least one sensor (7). Contrarily to this publication, the present invention utilizes the concept of absorption of vibrations by making use of a tuned mass-spring-damper system for the utilization of the energy absorbed from the damping in the various components of motion as driving force for vessels and generation of energy in vessels or floating bodies.
Published US Application 20090311925A1 to Hine, R. G. et al. concerns a wave-powered water vehicle which includes a surface float, a submerged swimmer, and a tether which connects the float and the swimmer, so that the swimmer moves up and down as a result of wave motion. The swimmer includes one or more fins which interact with the water as the swimmer moves up and down, and generate forces which propel the vehicle forward. The vehicle, which need not be manned, can carry communication and control equipment so that it can follow a course directed by signals sent to it, and so that it can record or transmit data from sensors on the vehicle. This water vehicle does not employ the tuned mass-spring-damper concept for the propulsion of the water vehicle.
The concept of the Suntory Mermaid II water vehicle involves the wave energy propulsion with the aid of two fins which move upwards and downwards following the waves, this driving the afts. Electric energy for consumption on board the water vehicle is provided by solar panels.
Analogously, the Orcelle concept ship designed for the sea transport of cars manufactured in Europe bound for Australia, besides propellers for propulsion utilizes fins which can also collect energy from waves. Besides other devices as fuel cells, the propulsion of this ship is also aided by sails which are further provided with solar energy collecting devices.
The Suntory Mermaid II as well as the Orcelle concept ship are vessels which do not correspond to the tuned mass-spring-damper concept for the motoring of same. Besides, these ships are provided with outer movable parts for harnessing energy from the wave motion, these parts being exposed to the well-known drawbacks of the harsh marine environment such as corrosion and formation of aggregates of some kinds of microorganisms.
The so-called WEGA—Wave Energy Gravitational Absorber—is a system designed by the Sea for Life Company. According to the International Publication WO 2010/080045 A1, the generating device is intended to harness the energy from the motion of sea waves for the generation of electric power. Said device is comprised of two identical floating bodies with a cylindrical shape (1), which will be exposed to the movement of waves. The two floating bodies are connected by means of arms (2) to a rotary axis (rotary in a plan perpendicular to the sea) (3), this being located on a rotating head (rotating in a plan parallel to the sea) (5), above the (usually predictable) reach of water, and around a mast (6) which is fixed to the sea bed. By action of sea waves, the floating cylinders, which have the buoyancy inherent to their volume and mass, will rise towards the crests and fall towards the troughs. So, an upward and downward circular movement is performed around the axis, where it will be harnessed by a hydraulic of other system (4). All the points which are susceptible of a dynamic seal will operate out of water. It is estimated that the device can harness from 100 to 150 kW of power. The device would at first be applied off shore and designed for producing energy for aquaculture, water desalination, maritime surveillance, tsunami detection, communication platforms, hydrogen production and energy for oil and gas platforms.
It should be pointed out that the system described in this International Publication bears no similarity with the concept of the present invention, which is directed to a tuned mass-spring-damper system having more than one degree of freedom (DOF) and tuned for the optimized utilization of the oscillations. Further, the device described in this International Publication is directed to the generation of energy solely, while the wave energy converter (WEC) which is the object of the present Application is directed to the motoring of vessels and on board energy generation, besides the generation of energy to land with more degrees of freedom for collecting the waves' energy.
Dampers which harness energy resulting from the relative movement of the suspension system of a vehicle such as an automobile are well-known.
Thus, Published US Application 20090260935 A1 to Avadhany, S. et al. relates to a regenerative shock absorber, that is, the shock absorbers harness the energy resulting from the relative motion of the suspension system of a vehicle. To this end, a piston is disposed for reciprocating motion within a cylinder as a vehicle's suspension system deflects. Hydraulic fluid passes through a hydraulic motor to turn its shaft. The hydraulic motor shaft is connected to an electric generator to generate electricity. Flow characteristics of hydraulic circuits are selected to provide suspension system damping for appropriate wheel control.
The energy removed from a conventional suspension system is lost as heat. There are known systems which try to recover the energy of a suspension system. For example, U.S. Pat. No. 7,261,171 to De La Torre, L. A. et al. shows an apparatus and its method of operation which convert relative movements between a vehicle wheel and a body of the vehicle to electricity that is used to recharge a battery of the vehicle. The apparatus includes a generator provided on the vehicle and a linear motion to rotary motion converter that is connected between a wheel of the vehicle and an armature of the generator. Reciprocating movements of the wheel relative to the vehicle body are converted by the motion converter to rotations of the armature in the generator which produces electricity for recharging the battery of the vehicle.
The concept of the present invention is patentably distinguishable from the previous and other references directed to energy converters in vehicles in that it is to be applied in water vehicles and floating bodies, but also for i) being not only regenerative, ii) include articulated external mobile parts which contact water as an option only and iii) do not include external parts designed for absorbing movement such as is the case of terrestrial transportation on wheels and suspension system.
The mandatory use of external, articulated mobile parts also occurs in the concept vehicles cited hereinbefore—Suntory Mermaid II and Orcelle—as fins, in this case the systems are not only regenerative.
A further, main distinction of the present Application includes the fact that the oscillating mass-spring-damper system of the converter of the invention bears more than one degree of freedom (DOF) of motion, so, when the WEC containing it is placed in a water vehicle or floating body, besides allowing the utilization of horizontal and vertical oscillations, it also makes possible the utilization of rotational oscillations.
Advantageously, the said mass-spring-damper system can also be automatically tuned for the optimization of the utilization of the energy of incident movements.
U.S. Pat. No. 7,443,046 to D. B. Stewart relates to a wave energy converter (WEC) which includes a shell suitable for being placed within a body of water. The shell contains an internal oscillator comprising a “reaction mass” and a spring mechanism coupled between the reaction mass and the shell. The shell and internal oscillator are constructed such that, when placed in a body of water and in response to waves in the body of water, there is relative motion between the shell and the internal oscillator's mass. A power take-off (PTO) device is coupled between the internal oscillator and the shell to convert their relative motion into electric energy. In systems embodying the invention, the spring mechanism is designed such that its displacement or movement is less than the displacement or movement of the reaction mass. Contrary to the concept of the present Application, the system described in this U.S. patent makes use of the mass-spring-damper concept for generating energy only, besides considering only one axis for the movement of the oscillating mass in the interior of the float, which limits the utilization of the energy in other dimensions of movement.
Published U.S. Application 20090085357 A1 to D. B. Stewart relates to a wave energy converter (WEC) system similar to that of U.S. Pat. No. 7,443,046 cited above. The WEC depicted in this document includes a shell containing an internal oscillator comprised of a reaction mass suspended from the shell by an elastic spring in parallel with a constant force spring. The constant force spring provides a relatively constant force (Fc) to counterbalance the static weight of the reaction mass and reduce the extension “static” length of the elastic spring while the elastic spring exerts a force (Fes) on the reaction mass that is proportional to the displacement, x, of the elastic spring. A power take-off (PTO) device, located within the shell, coupled between the shell and the internal oscillator converts their relative motion into electrical energy. Although this technology makes use of two springs in opposition, the configuration proposed bears only one degree of freedom, since the working mass moves along one single axis.
International Publication WO 2010/077158 A1 relates to a WEC which is the mechanical equivalent to a fully balanced 3-phase electrical generator, aimed to produce continuous power. By virtue of its 3-phase mechanic architecture, the WEC reacts force against himself and doesn't need any mooring system to react force against. The WEC is characterized by three equal legs (12,13,14), which are the three individual mechanical phases, all of them connected to a central articulation (1). The angle between each mechanical phase/leg (12,13,14) centre of mass (2,3,4) is exactly 120° degrees. Each leg/phase (12,13,14) must have the same inertia moment and is characterized by an equal large rigid mass (22,23,24) connected to each leg/phase (12,13,14). Only one of the three masses (22,23,24) interferes with Ocean waves, being the other two deeply submerged. Each leg/phase is connected by one of three equal springs (5,6,7) and one of three equal power-take-off dampers (8,9,10).
The WEC object of this International Publication is directed solely to the generation of energy, the propulsion of water vehicles being not included in the scope of this Publication. Such as described in the above document, the proposed device could not make possible the propulsion of a water vehicle. Besides, the described system operates in a condition of immersion in water, which means it is subject to corrosion and formation of aggregates of microorganisms. Further, the oscillating orbital movements described therein are limited to a single plan of vibration, which restricts the simultaneous utilization of the energy in further dimensions of movement. On the contrary, the radial arrangement of the present invention provides movement in all dimensions.
U.S. Pat. No. 7,658,067 to J. S. Gerber relates to a tunable WEC system where one or both of the floats used in the WEC has an internal spring system including a weight suspended from a spring mechanism having a selectively variable spring constant for allowing vertical oscillations of the weight in response to bobbing motions of the float The mechanical impedance of the system is a function of the oscillations of the weight, hence the system is tunable to selected values of mechanical impedance for optimal coupling with the prevailing waves.
The energy generation system described in the said U.S. document is applicable to floating bodies alone, the application of same for the propulsion of water vehicles being not considered in the U.S. Pat. No. 7,658,067. Further, only one axis of movement of the oscillating mass belonging to the float is provided, this feature restricting the utilization of the available energy in other dimensions of movement.
Thus, it is of interest to make available a WEC to be applied for i) the propulsion of water vehicles and simultaneous or alternate energy generation in these same water vehicles; ii) the generation of energy in floating bodies, the wave energy being that of waves themselves or any other incident mechanical disturbances, the WEC comprising a mass-spring-damper having different degrees of freedom (DOF) and automatic or manual tuning so as to maximize the energetic utilization of the oscillations within the limits of safety. WECs comprising more than one oscillating system are also envisaged, the operation being optimized for different oscillating conditions.